What Are Square Brackets

Square brackets [] are most commonly used in programming for:

• Defining and accessing elements of arrays or lists.
• Slicing or accessing subsets of arrays or lists.
• Accessing dictionary keys (in languages like Python and JavaScript).
• Type declarations in some languages (e.g., C# for arrays).
• Creating list comprehensions (in Python).
• Defining regular expressions (in many languages).
• Array destructuring (in JavaScript).

01. Arrays

Square brackets are commonly used to define and access elements of arrays or lists. In many programming languages like Python, JavaScript, and others, square brackets are used to create and work with ordered collections of items.

You can use square brackets to access specific elements by their index. Indexing typically starts from 0.

02. Regular Expressions

In some programming languages (like Python, JavaScript, Java), square brackets are used in regular expressions to define character classes. For example, \d matches any digit, but [0-9] explicitly defines the same range of digits.

In Conclusion

Square brackets are essential for working with collections, data structures, and regular expressions in many programming languages.